Prepare two large mixing bowl for dough 1 and 2 and add in flour, matcha powder (for dough 1) and baking powder and stir to mix well in each mixing bowl
Dissolve yeast in lukewarm milk and sugar. Once dissolves, let it sit for 5 minutes until they get foamy. Pour into the flour mixture, add in oil and mix well. Knead the doughs until they are smooth and doesn't stick to your hands anymore. You may need to add more flour or you may not. If the dough is still rather sticky, you may need to add a bit by a bit. Knead for about 10 minutes
Place each dough in a lightly oiled bowl to let it rest for about 1 hour or longer in winter time. It will double in size. Once they double in size, punch the down and knead for another minute
Dust your working area with some flour. Working with one dough at a time, roll each dough out into squares about 1/4-inch in thickness (about 10 x 10 inch size). Try to roll them out about the same size
Prepare your steamer and line with parchment paper. Place dough 1 or dough 2 (whichever color order you like) on a clean and lightly floured surface. Spread 1/2 of the pineapple jam onto dough 1, leaving about 1-inch on the side. Place dough 2 on top of it and spread the rest of the pineapple jam onto dough 2 , leaving about 1-inch on the side
Starting with the end near you, roll them up to the other end. So you have a long log-shape dough. Cut them into 8 or 10 equal size
Don't over crowd your steamer, you may need to steam in batches, that's fine, as the mantou will expand. Steam them on high heat for 10 minutes. Serve warm or room temperature